This invention has particular relation to the handling of paper sheet in the form commonly known as "broke" which results from a break in the paper web as it is being produced on a paper machine, and the invention is especially concerned with the handling and repulping of such broke.
It has long been known to provide for the handling and repulping of broke by means of pulpers which are positioned underneath the paper machine at spaced locations where breaks in the web are likely to occur such, for example, as between the last dryer drum and the adjacent calendar stack. It is also a common practice to utilize for this purpose a pulper having an elongated but relatively narrow tub which can be positioned to extend across the width of the paper machine so that when a web break occurs, the advancing web of broke can be directed into the tub without requiring slitting, folding or redirection.
An early form of pulper for this purpose is disclosed in the co-owned Stark U.S. Pat. No. 2,696,766 of 1954. The assignee of the present invention has also marketed broke pulpers comprising an elongated open tub having mounted in one of its side walls one or more rotors of the construction shown in the co-owned Vokes U.S. Pat. No. 3,073,535 of 1963 or Couture U.S. Pat. No. 3,889,885 of 1975.
Problems have been encountered with broke pulpers of the above types in the handling of broke which has been pressed and dried sufficiently to possess significant tensile strength to behave like a sheet as compared with a newly formed web. Such broke has a tendency to pile up on top of the liquid in the tub and thereby to avoid the repulping action of the rotor or rotors submerged in the liquid in the tub. The present invention is directed to curing this problem by providing a modified pulper construction which will assure rapid subjection of any type of broke to the repulping action of the rotor or rotors within the pulper tub.